Master Class – Perfecting Your Mix

I like to tell my clients that a great mix happens in the last
five minutes of work. Because an adjustment on one track
can change the way the entire mix sounds, the final tweaks
make everything fall into place.

Getting there, however, is fraught with danger. Make
the lead vocal a couple dB too loud, and the backing
tracks will sound wimpy. Allow the guitars too much low-midrange
tone to give them warmth and girth, and the
mix’s bottom end will sound blurry. Bump up the reverb
returns a tad too much, and the wonderful punch you
crafted on the kick and bass will go out the window. A few
misplaced adjustments are all it takes to disfigure your
mix. But conversely, the right nip and tuck will transform
it from middling to magnificent.

In this article, I’ll offer pointers on deciphering what’s
wrong with a disappointing mix and how to correct it. But
first, it’s important to mention a common mistake that robs
a mix’s potential fresh out of the gate.

Fig. 1. The center LED ladders for the Brainworx bx_meter show your mix’s dynamic range in decibels. The farther the LEDs extend down from the top of the meters (0dB), the greater your mix’s crest factor.

Avoid Headroom Hara-kiri Starting your
mixdown session with all faders close to 0dB
is a recipe for distortion and a harsh-sounding
mix. On a mix with lots of tracks, start with all
faders set considerably lower in order to give
your master bus plenty of headroom. You can
always raise your master bus fader (or makeup
gain for a pre-fader bus compressor) to compensate
for any deficit in level, but lowering
the master fader won’t undo clipping that occurs
at the bus’ input.

If you run out of headroom, you can group
all faders for tracks and auxes and pull them
down the same amount to prevent clipping
the master bus. But because faders usually
have logarithmic tapers, linear adjustments
across the board won’t fully preserve your
carefully wrought balance. Additionally, any
pre-fader effects will end up sounding relatively
too loud after you lower faders for the
tracks that are bussed to those effects. The
upshot: Give your master bus more headroom
than you think it’ll need.

Watch Your Crest Factor We all know that
too much bus compression can make a mix
sound harsh and fatiguing. But how do you
know when your mix is too hot? While the best
guides are your ears, meters that display your
mix’s crest factor will also alert you you’ve
strayed too close to the sun.

Crest factor is the difference between peak
and RMS (or average) levels. The lower your
mix’s crest factor, the lower its dynamic range
and the harsher your mix will sound. A good
rule of thumb is your mix should never have a
crest factor lower than 6dB (and that’s pushing
it). If your project will be professionally
mastered, aim for a crest factor of around 10 to
12dB and let the mastering engineer tweak the
dynamic range with his or her superior tools.

Excellent plug-ins that simultaneously
show peak and RMS levels include the Waves
Dorrough Meter Collection (a bundle) and
Brainworx bx_meter. bx_meter also includes
a dynamic-range meter that shows your crest
factor in decibels (see Figure 1), relieving you
from computing the difference between peak and
RMS values. Instantiate Dorrough or bx_meter
post-fader and after all other plug-ins on your
master bus.

If you’re using light or no compression on
your master bus and your mix’s crest factor is
still too low, your drum tracks might be mixed
too quietly or have insufficient attack. Assuming
you have enough headroom, try goosing
your kick and snare tracks or adding the SPL
Transient Designer or Waves TransX plug-in to
those tracks to sharpen their strikes (see Figure
2). As always, use your ears to gauge whether
you’ve improved your mix or simply made the
meters look better!

Hunt Down Distortion Every channel of
your mix should have its meters set up to hold
clips indefinitely (using infinite-hold mode).
After you play through your mix, stop the
transport and look to see if clipping occurred
in any channel. Check every stage possible for
the signal chain (pre- and post-EQ, pre- and
post-dynamics and so on) and lower input or
output levels wherever clipping occurred to
prevent distortion on the next pass through.
Just keep in mind that the meters for 32-bit
(and higher-resolution) plug-ins may indicate
clipping where none has occurred; they show
“overs” to warn you that the output of your
DAW’s mixer (which might be constrained to
24-bit depth and lower headroom) might clip
at its output.

Fig. 2. The Waves TransX plug-in can be used to increase the attack of trap drums and make your mix sound more dynamic.

For mixes with tons of tracks, the hunt for
clipping can entail a lot of work, but it’s worth
it. A tiny bit of distortion on each of several
tracks can produce an edgy or harsh-sounding
mix that no amount of equalization and warming
with tube-emulation plug-ins will fix. If
you’re pressed for time, at the very least check
for clipping on non-percussive tracks such as
vocals, string pads and organ; distortion will
be most noticeable on sources such as these
that produce high RMS levels. You can often
get away with some clipping on trap drums; in
fact, subtle grit and rounding from mild clipping
sometimes sounds great on traps (especially
kick and snare).

Check the Width Mixes can sound too
narrow if too many tracks are panned close
to center, center-panned tracks are too loud,
or your mix has too much bottom end. Bass
frequencies tend to be highly correlated in left
and right channels of stereo tracks; too much
bass on a stereo track can therefore cause its
image to narrow.

A phase-correlation meter is an excellent
tool for checking the width of your
mix. The aforementioned Waves Dorrough
and Brainworx bx_meter plug-ins each provide
excellent phase-correlation metering
(see Figure 3). If the meter spends most of
its time close to the positive extreme of its
range (far-right on a horizontally oriented
meter), your mix is probably too narrow
and trending toward a mono soundstage.
Conversely, if the phase-correlation reading
spends more than a brief amount of time to
the left of center, your mix is too decorrelated;
in that case, it will likely sound washy
and it won’t be mono-compatible.

Fig. 3. The Waves Dorrough Meter plug-in includes a phase mode useful for gauging the width and mono-compatibility of your mix. Readings consistently far to the right of center indicate a mix that is relatively narrow.

For a mix that’s too narrow, consider hard-panning
one or more tracks, especially those
with lots of high-frequency content (such as
shakers or cymbals). Try thinning out bass
frequencies on stereo tracks. See if lowering
the bass guitar helps widen the mix without
making it sound too bright or thin. Your phase-correlation
meter should help you visualize
when your mix is spacious enough. As when
monitoring crest factor, place your phase-correlation
meter post-fader on your master bus
and after all other plug-ins.

Use Stereo Imagers Prudently Another
way to widen a mix is to use a stereo imager
on the mix bus. Injudicious program-width
enhancement, however, will lower the level of
the kick, snare, bass, and vocals too much and
make your mix lose punch. Instead of placing
an imager on the mix bus, try widening
individual stereo tracks instead. An imager
can sound terrific on stereo tracks and auxes
that contain a lot of ambience, such as reverb
returns and room mics for drums. If
your imager is multiband, try narrowing
the bass frequencies to mono and widening
only the highs; Ozone 5 Advanced includes
a stereo imager that works great for this
application (see Figure 4). As you work,
check the mix bus’ phase-correlation meter
to make sure you’re not fattening the cow
too much.

Get the Bottom End in Proper Balance
The toughest aspect of mixing is getting the
bass frequencies in proper balance with mids
and highs. If your mix sounds too muddy
and the kick and bass guitar can’t be clearly
heard, chances are that bass frequencies
in other tracks are masking them. Try cutting
bass frequencies in guitar and keyboard
comp tracks (and any other tracks that don’t
need a big bottom) to make room in the low
end of your mix for the bass and kick to
voice more clearly.

If the bass guitar sounds plenty loud but
the bottom end of your mix still sounds thin,
try lowering the bass track and boosting its
bass frequencies. The same strategy often
works for kick drum. In most cases, the bass
guitar will benefit from heavy compression or
limiting to make it ride at a fairly consistent
level in the mix.

Of course, you’ll never get the bottom end
of your mix in proper perspective if you can’t
hear it. Tweaking the bottom two octaves of a
mix while listening to monitors with weak bass
response makes about as much sense as painting
a portrait with sunglasses on. It’s critical to listen
to your mix with a subwoofer or full-range
monitors—and in an accurate room—to make
sure you aren’t adding too much bass to the mix.
If your speakers and control room aren’t up to
the task, check your mix on headphones that
have flat and extended bass response.

It’s equally important to make sure the bass
and kick don’t disappear when listening back
on midrangey speakers. Band-limited consumer
proxies such as Yamaha NS-10M Studio
and Avant Electronics Avantone MixCubes
are great monitors for this purpose. Alternatively,
see how the bass instruments sound on
a home or car stereo, computer speakers, or a
boom box. If you can’t hear the kick and bass
on these speakers, they’re probably mixed too
low. If kick drum hits clip the speakers on your
boom box (set to flat EQ), the kick probably
has too much bottom end.

Solo the Side Channel If you find yourself
struggling to get enough bottom end on your
mix and boosting the bass frequencies on your
kick drum track isn’t helping, your kick drum
might be out-of-phase. This is sometimes a
problem when poor stereo kick drum samples
are used in a production. The way to tell if
this is the case is by soloing the side channel,
using a plug-in such as the Brainworx
bx_meter or bx_control V2 that provides
mid/side monitoring. If you hear the kick
drum’s dry sound while soloing the side
channel, your kick drum is out-of-phase and
no amount of bass-EQ boost will give you the
bottom end your mix needs. Adjust the phase
on one channel of the kick sample or replace
the sample with one that’s in-phase.

Check Levels for Vocals and Guitar Solos
To place the lead vocal in proper perspective,
check your mix on midrange-y monitors
that have weak bass response. (Listening to
monitors with ample bass response makes the
tests I’m about to describe more difficult; you
want to use speakers that provide an isolated
window into the midrange band, where vocals
and guitars mostly reside.) While listening to
your mix, confirm that the background vocals
aren’t louder than the lead vocal. Also make
sure overlapping guitar fills don’t obscure any
lyrics; ride the guitar’s fader down in spots
where it would otherwise mask the money
track. Generally speaking, a guitar solo should
not be louder than the lead vocal; if it is, the
vocal will sound under-powered when it reenters
after the solo.

While the lead vocal is singing, turn your
midrange-y monitors down to the point where
they’re barely audible. If the lead vocal disappears
before the instrumental tracks do, it’s
mixed too low. Be sure to also check how the
lead vocal sounds on full-bandwidth monitors.
Many two-way monitors have crossovers
that recede midrange elements such as vocals
slightly into the background. Make sure the lead
vocal can still be clearly heard on such monitors
and on all other systems you have access to.

Keep Notes A great mix might require a few
hundred or more dynamic adjustments to fader
levels, EQ, panning, and effects parameters.
Keeping mental track of the net effect of each
of these moves is a daunting task, and it’s easy
to miss the forest for the trees. When you think
your mix is finally in great shape, listen back on
all the monitors at your disposal and take notes
of any problems you hear. Make a checklist of
changes you’d like to make in a remix to fix those
problems: “Boost the bass guitar’s EQ around 1dB
at 200Hz” (if it sounds too thin on midrange-y
speakers), “dip the lead guitar solo on the last
note coming back into the final chorus” (if it obscures
the vocals), and so on. Then mix the song
again, incorporating the ideas in your checklist.

Listening back to the mix that you’ve
tweaked, you’re likely to hear additional
problems you didn’t previously notice or that
were introduced by the new mix moves. Make
a new checklist and mix again. Repeat the
process until you have no more complaints.
Your mix is now killer.

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